Implants refer to materials and components which are introduced into a human or animal body in order to fulfill certain replacement or additional functions for a limited period of time or for life. Replacement functions include for example the assistance, control or partial or complete replacement of organ functions or also the assistance of healing processes, for example the immobilization of a bone fracture by means of osteosynthesis. In the case of osteosynthesis, implants which are usually made from metal are fixed to the bone, for example by means of nails or screws.
Artificial cardiac pacemakers for stimulating the heart are known from cardiac surgery. Cardiac pacemakers essentially comprise one or more electrodes which are fixed to the myocardium by sutures. For example, document EP 0 634 191 A2 discloses an implantable defibrillator comprising a flat electrode in the form of a mesh, a coil or a fabric made from electrically conductive material or comprising an intracardial electrode in the form of a coil made from electrically conductive material, wherein the electrode is completely embedded in a biocompatible, hydrophilic, electrolytically conductive polymer or is coated with such a polymer. The defibrillator is fixed in the subcutaneous tissue by customary fixing means such as barbs and pins.
Furthermore, so-called gastric pacemakers are known from obesity therapy. Gastric pacemakers generally consist of two electrodes which are introduced into the gastric wall by means of a needle. A wire connects the electrodes to a pacemaker, which is placed in a subcutaneous pocket below the left costal arch and can be programmed from outside. In the region of the gastroesophageal transition, a suitable location on the gastric wall is selected at which the electrodes are intended to come to rest intramurally, that is to say in the organ wall. The entry and exit point of the needle are usually approximately 2.5 cm apart, with the entry and exit points being marked by an electrocauter. The electrodes are then introduced under gastroscopic monitoring, in order to prevent any perforation of the gastric wall. The probe is secured proximally by two sutures and distally by means of a clip or a barb. The lead is then passed outside the body and connected there to the pacemaker. Also known are implantable gastric bands which are placed around the fundus of the stomach in a laparoscopic operation. The gastric band may be made for example from silicone. By constricting the diameter of the stomach, a long-term significant reduction in weight is said to be achieved since then a smaller amount of food is sufficient to reduce or eliminate the feeling of hunger of the patient.
From reflux surgery, various devices are known which can be implanted in the body in order to reduce reflux. The term “reflux” generally refers in medicine to a pathological return flow from one hollow organ to another. Examples of refluxes include: gastroesophageal reflux—from the stomach to the esophagus, which may lead to heartburn or to reflux esophagitis; hepatojugular reflux—from the heart to the external jugular vein in the event of pressure on the liver; and vesicorenal reflux—from the urinary bladder via the ureter to the kidney. Such a device which can be implanted in the body consists of a mesh which is placed around the esophagus. Clinical and experimental studies, particularly in hernia surgery and in reflux surgery, have shown that such meshes are well accepted by the body and do not exhibit any tendency to migrate through organs.
One common feature of all known implants is the need to fix the implant securely to an organ or to an organ part. The term “organ” generally refers in medicine to parts of the body which are composed of cells and tissue and which form a unit having specific functions, for example the esophagus, the stomach, the intestine, the esophageal sphincter, the bladder muscle, other sphincters. The fixing operation often leads to traumatic damage to the organ. For example, when fixing the electrodes of a gastric pacemaker, such damage may lead to a weakness of the gastric wall, which might result in a rupture of the gastric wall. However, if the electrodes are fixed in such a way that damage to the gastric wall is largely avoided, the probability of the electrodes slipping in the gastric wall or even slipping out of the gastric wall would be significantly increased as a result.
Known implantable devices have the disadvantage that fixing to an organ or to an organ part causes traumatic damage to the organ wall, wherein the devices often dislocate despite being fixed.